Get command keys for subcommands

[dvora-h]

Pull Request check-list

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Description of change

fixes #2165

[codecov-commenter]

Codecov Report

Merging #2170 (bda5864) into master (5c99e27) will decrease coverage by 0.08%.
The diff coverage is 10.34%.

@@            Coverage Diff             @@
##           master    #2170      +/-   ##
==========================================
- Coverage   91.98%   91.89%   -0.09%     
==========================================
  Files         105      105              
  Lines       25287    25313      +26     
==========================================
+ Hits        23260    23262       +2     
- Misses       2027     2051      +24     

Impacted Files	Coverage Δ
redis/cluster.py	91.72% <ø> (ø)
tests/test_cluster.py	97.54% <ø> (+0.05%)	⬆️
redis/commands/parser.py	68.13% <4.34%> (-20.28%)	⬇️
redis/client.py	88.76% <25.00%> (-0.28%)	⬇️
tests/test_commands.py	90.04% <50.00%> (+<0.01%)	⬆️
redis/asyncio/client.py	91.98% <0.00%> (-0.18%)	⬇️

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